From German patent publication DE 199 28 185 B4 and U.S. Pat. No. 6,617,766 B1, a piezoelectric element is known that is pressed onto a mounting or support plate by means of a bias spring and a helical spring plate arranged above the bias spring.
From WO 2005/062395 and US counterpart 2007/0252474 A1, a piezoelectric actuator is known with a tubular spring element provided with recesses.
From US 2003/034594 A1, a piezoelectric actuator is similarly known with a tubular spring element provided with recesses.